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Sep 18, 2013
09/13
by
Tod R. Lauer
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I have combined the Emsellem et al. ATLAS3D rotation measures of a large sample of early-type galaxies with HST-based classifications of their central structure to characterize the rotation velocities of galaxies with cores. "Core galaxies" rotate slowly, while "power-law galaxies" (galaxies that lack cores) rotate rapidly, confirming the analysis of Faber et al. Significantly, the amplitude of rotation sharply discriminates between the two types in the -19 > Mv > -22...
Source: http://arxiv.org/abs/1209.4357v1
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66
Sep 20, 2013
09/13
by
Tod R. Lauer
texts
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Undersampled images, such as those produced by the HST WFPC-2, misrepresent fine-scale structure intrinsic to the astronomical sources being imaged. Analyzing such images is difficult on scales close to their resolution limits and may produce erroneous results. A set of ``dithered'' images of an astronomical source generally contains more information about its structure than any single undersampled image, however, and may permit reconstruction of a ``superimage'' with Nyquist sampling. I...
Source: http://arxiv.org/abs/astro-ph/9810394v1
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Sep 21, 2013
09/13
by
Tod R. Lauer
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An undersampled point spread function may interact with the microstructure of a solid-state detector such that the total flux detected can depend sensitively on where the PSF center falls within a pixel. Such intra-pixel sensitivity variations will not be corrected by flat field calibration and may limit the accuracy of stellar photometry conducted with undersampled images, as are typical for Hubble Space Telescope observations. The total flux in a stellar image can vary by up to 0.03 mag in...
Source: http://arxiv.org/abs/astro-ph/9907100v1
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Sep 19, 2013
09/13
by
Tod R. Lauer
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Application of deconvolution algorithms to astronomical images is often limited by variations in PSF structure over the domain of the images. One major difficulty is that Fourier methods can no longer be used for fast convolutions over the entire images. However, if the PSF is modeled as a sum of orthogonal functions that are individually constant in form over the images, but whose relative amplitudes encode the PSF spatial variability, then separation of variables again allows global image...
Source: http://arxiv.org/abs/astro-ph/0208247v1
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Sep 21, 2009
09/09
by
*Credit:* Tod R. Lauer/NASA [ http://www.nasa.gov/ ]
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*Description*: NASA's Hubble Space Telescope clearly shows the central core of the elliptical galaxy M32. This green-light image was taken with HST's Wide Field and Planetary Camera (WFPC), in high resolution mode, on August 17, 1991. The steady increase in brightness of M32 towards its center is readily apparent in the image, showing that the stars in M32 are strongly concentrated towards its nucleus, as if drawn into the center and held there by the gravitational field of a massive black...
Topics: M32, What -- Hubble Space Telescope (HST), Where -- M32
Source: http://hubblesite.org/newscenter/archive/releases/1992/09/image/a/
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Sep 22, 2013
09/13
by
Tod R. Lauer; Todd A. Boroson
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We present HST WFPC2/PC images and KPNO 4-m longslit spectroscopy of the QSO SDSS J153636.22+044127.0, which we advanced as a candidate binary supermassive black hole. The images reveal a close companion coincident with the radio source identified by Wrobel & Laor (2009). It appears to be consistent with a M_g ~ -21.4 elliptical galaxy, if it is at the QSO redshift. The spectroscopy, however, shows no spatial offset of the red or blue Balmer line subcomponents. The companion is thus not the...
Source: http://arxiv.org/abs/0906.0020v2
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73
Jul 19, 2013
07/13
by
Todd A. Boroson; Tod R. Lauer
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The Karhunen-Loeve (KL) transform can compactly represent the information contained in large, complex datasets, cleanly eliminating noise from the data and identifying elements of the dataset with extreme or inconsistent characteristics. We develop techniques to apply the KL transform to the 4000-5700A region of 9,800 QSO spectra with z < 0.619 from the SDSS archive. Up to 200 eigenspectra are needed to fully reconstruct the spectra in this sample to the limit of their signal/noise. We...
Source: http://arxiv.org/abs/1005.0028v2
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Sep 18, 2013
09/13
by
Tod R. Lauer; Scott Tremaine; Douglas Richstone; S. M. Faber
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Programs to observe evolution in the Mbh-sigma or Mbh-L relations typically compare black-hole masses, Mbh, in high-redshift galaxies selected by nuclear activity to Mbh in local galaxies selected by luminosity L, or stellar velocity dispersion sigma. Because AGN luminosity is likely to depend on Mbh, selection effects are different for high-redshift and local samples, potentially producing a false signal of evolution. This bias arises because cosmic scatter in the Mbh-sigma and Mbh-L relations...
Source: http://arxiv.org/abs/0705.4103v1
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31
Sep 20, 2013
09/13
by
Alister Graham; Tod R. Lauer; Matthew Colless; Marc Postman
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We model the surface brightness profiles of a sample of 119 Abell Brightest Cluster Galaxies (BCG), finding a generalised deVaucouleurs R^{1/n} law, where n is a free parameter, to be appropriate. Departures from the R^{1/4} law are shown to be a real feature of galaxy profiles, not due to observational errors or coupling of n with the other model parameters. BCG typically have values of n greater than 4. The shape parameter n is shown to correlate with effective half-light radius, such that...
Source: http://arxiv.org/abs/astro-ph/9603006v1
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Sep 19, 2013
09/13
by
Marc Postman; Tod R. Lauer; Istvan Szapudi; William Oegerle
texts
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We present constraints on the evolution of large-scale structure from a catalog of 710,000 galaxies with I_AB
Source: http://arxiv.org/abs/astro-ph/9804141v2
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Sep 24, 2013
09/13
by
Marc Postman; Tod R. Lauer; William Oegerle; Megan Donahue
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eye 31
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We have conducted an automated search for galaxy clusters within a contiguous 16 square degree I-band survey in the north Galactic hemisphere. A matched filter detection algorithm identifies 444 cluster candidates in the range 0.2
Source: http://arxiv.org/abs/astro-ph/0205513v2
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Sep 18, 2013
09/13
by
István Szapudi; Marc Postman; Tod R. Lauer; William Oegerle
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Constraints on the validity of the hierarchical gravitational instability theory and the evolution of biasing are presented based upon measurements of higher order clustering statistics in the Deeprange Survey, a catalog of $\sim710,000$ galaxies with $I_{AB} \le 24$ derived from a KPNO 4m CCD imaging survey of a contiguous $4^{\circ} \times 4^{\circ}$ region. We compute the 3-point and 4-point angular correlation functions using a direct estimation for the former and the counts-in-cells...
Source: http://arxiv.org/abs/astro-ph/0008131v2
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Sep 22, 2013
09/13
by
Philip F. Hopkins; Thomas J. Cox; Suvendra N. Dutta; Lars Hernquist; John Kormendy; Tod R. Lauer
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We study the origin and properties of 'extra' or 'excess' central light in the surface brightness profiles of cusp or power-law ellipticals. Dissipational mergers give rise to two-component profiles: an outer profile established by violent relaxation acting on stars present in the progenitors prior to the final merger, and an inner stellar population comprising the extra light, formed in a compact starburst. Combining a large set of hydrodynamical simulations with data that span a broad range...
Source: http://arxiv.org/abs/0805.3533v2
1
1.0
Jun 30, 2018
06/18
by
Tod R. Lauer; Marc Postman; Michael A. Strauss; Genevieve J. Graves; Nora E. Chisari
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We have observed 433 z
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1407.2260
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Sep 24, 2013
09/13
by
Tod R. Lauer; Ralf Bender; John Kormendy; Philip Rosenfield; Richard F. Green
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We obtained U_330 and B band images of the M31 nucleus using the High Resolution Camera of the Advanced Camera for Surveys on board the Hubble Space Telescope (HST). The spatial resolution in the U_330-band, 0.03" FWHM, or 0.1 pc at M31, is sufficient to resolve the outskirts of the compact cluster (P3) of UV-bright stars surrounding the M31 black hole. The center of the cluster is marked by an extended source that is both brighter and redder than the other point sources within P3; it is...
Source: http://arxiv.org/abs/1112.1419v1
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27
Sep 22, 2013
09/13
by
Christopher Z. Waters; Stephen E. Zepf; Tod R. Lauer; Edward A. Baltz
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eye 27
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We present an analysis of a 50 orbit HST ACS observation of the M87 globular cluster system. We use the extraordinary depth of this dataset to test whether the colors and magnitudes show evidence for a mass-metallicity relation in globular cluster populations. We find only a weak or absent relation between the colors and magnitudes of the metal poor subpopulation of globular clusters. The weakness or absence of a color-magnitude relation is established over a wide range in luminosity from...
Source: http://arxiv.org/abs/0811.0391v1
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Sep 23, 2013
09/13
by
Tod R. Lauer; S. M. Faber; Edward A. Ajhar; Carl J. Grillmair; Paul A. Scowen
texts
eye 28
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WFPC-2 images are used to study the central structure of M31, M32, and M33. The dimmer peak, P2, of the M31 double nucleus is centered on the bulge to 0.1", implying that it is the dynamical center of M31. P2 contains a compact source discovered by King et al. (1995) at 1700 A. This source is resolved, with r_{1/2} approx0.2 pc. It dominates the nucleus at 3000 A, and is consistent with late B-early A stars. This probable cluster may consist of young stars and be an older version of the...
Source: http://arxiv.org/abs/astro-ph/9806277v1
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Sep 22, 2013
09/13
by
Tod R. Lauer; John L. Tonry; Marc Postman; Edward A. Ajhar; Jon A. Holtzman
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We used HST to obtain surface brightness fluctuation (SBF) observations of four nearby brightest cluster galaxies (BCG) to calibrate the BCG Hubble diagram of Lauer & Postman (1992). This BCG Hubble diagram contains 114 galaxies covering the full celestial sphere and is volume limited to 15,000 km/s, providing excellent sampling of the far field Hubble flow. The SBF zero point is based on the Cepheid calibration of the ground I_KC method (Tonry et al. 1997) as extended to the WFPC2 F814W...
Source: http://arxiv.org/abs/astro-ph/9708252v1
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Sep 18, 2013
09/13
by
Michael M. Shara; David R. Zurek; Edward A. Baltz; Tod R. Lauer; Joseph Silk
texts
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Only one certain classical nova eruption has ever been detected inside a globular cluster - nova 1860 A.D. (T Sco) in M80. During a survey of M87 we have detected an erupting star coincident (to within 0.08 pixels) with a globular cluster of that giant elliptical galaxy. We are able to discount variables in the foreground or background of M87. The light curve and color of the erupting star match those expected for a nova at the distance of M87. The chance superposition of an M87 field nova on...
Source: http://arxiv.org/abs/astro-ph/0401444v1
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Sep 18, 2013
09/13
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Philip F. Hopkins; Tod R. Lauer; Thomas J. Cox; Lars Hernquist; John Kormendy
texts
eye 30
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We investigate how 'extra' central light in the surface brightness profiles of cusp ellipticals relates to the profiles of ellipticals with cores. Cusp elliptical envelopes are formed by violent relaxation in mergers acting on stars in progenitor disks, while their centers are structured by dissipational starbursts. Core ellipticals are formed by subsequent merging of (now gas-poor) cusp ellipticals, with the fossil starburst components combining to preserve a compact component in the remnant...
Source: http://arxiv.org/abs/0806.2325v2
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Sep 21, 2013
09/13
by
Yujin Yang; Ann I. Zabludoff; Dennis Zaritsky; Tod R. Lauer; J. Christopher Mihos
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We present HST/WFPC2 observations of the five bluest E+A galaxies (z~0.1) in the Zabludoff et al. sample to study whether their detailed morphologies are consistent with late-to-early type evolution and to determine what drives that evolution. The morphologies of four galaxies are disturbed, indicating that a galaxy-galaxy merger is at least one mechanism that leads to the E+A phase. Two-dimensional image fitting shows that the E+As are generally bulge-dominated systems, even though at least...
Source: http://arxiv.org/abs/astro-ph/0402062v1
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Sep 23, 2013
09/13
by
M. A. Strauss; R. Cen; J. P. Ostriker; T. R. Lauer; M. Postman
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Lauer \& Postman (LP) observe that all Abell clusters with redshifts less than 15,000\kms\ appear to be participating in a bulk flow of 689 km s$^{-1}$ with respect to the Cosmic Microwave Background. We find this result difficult to reconcile with all popular models for large-scale structure formation that assume Gaussian initial conditions. This conclusion is based on Monte-Carlo realizations of the LP data, drawn from large Particle-Mesh $N$-body simulations. We have taken special care...
Source: http://arxiv.org/abs/astro-ph/9406038v1
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27
Sep 20, 2013
09/13
by
Christopher Z. Waters; Stephen E. Zepf; Tod R. Lauer; Edward A. Baltz; Joseph Silk
texts
eye 27
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We present the luminosity function to very faint magnitudes for the globular clusters in M87, based on a 30 orbit \textit{Hubble Space Telescope (HST)} WFPC2 imaging program. The very deep images and corresponding improved false source rejection allow us to probe the mass function further beyond the turnover than has been done before. We compare our luminosity function to those that have been observed in the past, and confirm the similarity of the turnover luminosity between M87 and the Milky...
Source: http://arxiv.org/abs/astro-ph/0607238v1
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Sep 22, 2013
09/13
by
J. L. Bazo Alba; E. Bernardini; R. Lauer; for the IceCube Collaboration
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A time-dependent search for neutrino flares from pre-defined directions in the whole sky is presented. The analysis uses a time clustering algorithm combined with an unbinned likelihood method. This algorithm provides a search for significant neutrino flares over time-scales that are not fixed a-priori and that are not triggered by multiwavelength observations. The event selection is optimized to maximize the discovery potential, taking into account different time-scales of source activity and...
Source: http://arxiv.org/abs/0908.4209v1
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Sep 18, 2013
09/13
by
Michael J. I. Brown; Arjun Dey; Buell T. Jannuzi; Tod R. Lauer; Glenn P. Tiede; Valerie J. Mikles
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We have measured the clustering of z 1000 galaxies to be selected as a function of spectral type, absolute magnitude, and photometric redshift. Spectral synthesis models can be used to predict the colors and luminosities of a galaxy population as a function of redshift. We have used PEGASE2 models, with exponentially declining star formation rates, to estimate the observed colors and luminosity evolution of galaxies and to connect, as an evolutionary sequence, related populations of galaxies at...
Source: http://arxiv.org/abs/astro-ph/0306128v3
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72
Jul 20, 2013
07/13
by
John R. Jardel; Karl Gebhardt; Juntai Shen; David Fisher; John Kormendy; Jeffry Kinzler; Tod R. Lauer; Douglas Richstone; Kayhan Gültekin
texts
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We present axisymmetric, orbit-based models to study the central black hole, stellar mass-to-light ratio, and dark matter halo of NGC 4594 (M104, the Sombrero Galaxy). For stellar kinematics, we use published high-resolution kinematics of the central region taken with the Hubble Space Telescope, newly obtained Gemini long-slit spectra of the major axis, and integral field kinematics from the SAURON instrument. At large radii, we use globular cluster kinematics to trace the mass profile and...
Source: http://arxiv.org/abs/1107.1238v1
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Sep 23, 2013
09/13
by
Nicholas J. McConnell; Shi-Fan S. Chen; Chung-Pei Ma; Jenny E. Greene; Tod R. Lauer; Karl Gebhardt
texts
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We have tested the effect of spatial gradients in stellar mass-to-light ratio (Y) on measurements of black hole masses (MBH) derived from stellar orbit superposition models. Such models construct a static gravitational potential for a galaxy and its central black hole, but typically assume spatially uniform Y. We have modeled three giant elliptical galaxies with gradients alpha = d(log Y)/d(log r) from -0.2 to +0.1. Color and line strength gradients suggest mildly negative alpha in these...
Source: http://arxiv.org/abs/1303.4393v1
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27
Sep 23, 2013
09/13
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Ata Sarajedini; Conor L. Mancone; Tod R. Lauer; Alan Dressler; Wendy Freedman; S. C. Trager; Carl Grillmair; Kenneth J. Mighell
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We present Hubble Space Telescope observations taken with the Advanced Camera for Surveys Wide Field Channel of two fields near M32 - between four and six kpc from the center of M31. The data cover a time baseline sufficient for the identification and characterization of 681 RR Lyrae variables of which 555 are ab-type and 126 are c-type. The mean magnitude of these stars is =25.29 +/- 0.05 where the uncertainty combines both the random and systematic errors. The location of the stars in the...
Source: http://arxiv.org/abs/0904.4290v1
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Sep 21, 2013
09/13
by
Antonela Monachesi; Scott C. Trager; Tod R. Lauer; Wendy Freedman; Alan Dressler; Carl Grillmair; Kenneth J. Mighell
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We present the deepest optical color-magnitude diagram (CMD) to date of the local elliptical galaxy M32. We have obtained F435W and F555W photometry based on HST ACS/HRC images for a region 110" from the center of M32 and a background field about 320" away from M32 center. Due to the high resolution of our Nyquist-sampled images, the small photometric errors, and the depth of our data we obtain the most detailed resolved photometric study of M32 yet. Deconvolution of HST images proves...
Source: http://arxiv.org/abs/1011.0582v2
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Sep 19, 2013
09/13
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S. Tremaine. D. O. Richstone; Y. -I. Byun; A. Dressler; S. M. Faber; C. Grillmair; J. Kormendy; T. R. Lauer
texts
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We describe a one-parameter family of models of stable spherical stellar systems in which the phase-space distribution function depends only on energy. The models have similar density profiles in their outer parts ($\rho\propto r^{-4}$) and central power-law density cusps, $\rho\propto r^{3-\eta}$, $0
Source: http://arxiv.org/abs/astro-ph/9309044v1
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29
Sep 21, 2013
09/13
by
Kayhan Gultekin; Douglas O. Richstone; Karl Gebhardt; S. M. Faber; Tod R. Lauer; Ralf Bender; John Kormendy; Jason Pinkney
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We present HST STIS observations of the galaxy NGC 4382 (M85) and axisymmetric models of the galaxy to determine mass-to-light ration (M/L, V-band) and central black hole mass (M_BH). We find M/L = 3.74 +/- 0.1 (solar units) and M_BH = 1.3 (+5.2, -1.2) \times 10^7 M_sun at an assumed distance of 17.9 Mpc, consistent with no black hole. The upper limit, M_BH < 9.6 \times 10^7 M_sun (2{\sigma}) or M_BH < 1.4 \times 10^8 M_sun (3{\sigma}) is consistent with the current M-{\sigma} relation,...
Source: http://arxiv.org/abs/1108.1808v1
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44
Sep 22, 2013
09/13
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Karl Gebhardt; Joshua Adams; Douglas Richstone; Tod R. Lauer; S. M. Faber; Kayhan Gultekin; Jeremy Murphy; Scott Tremaine
texts
eye 44
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We present the stellar kinematics in the central 2" of the luminous elliptical galaxy M87 (NGC 4486), using laser adaptive optics to feed the Gemini telescope integral-field spectrograph, NIFS. The velocity dispersion rises to 480 km/s at 0.2". We combine these data with extensive stellar kinematics out to large radii to derive a black-hole mass equal to (6.6+-0.4)x10^9 Msun, using orbit-based axisymmetric models and including only the NIFS data in the central region. Including...
Source: http://arxiv.org/abs/1101.1954v1
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34
Sep 19, 2013
09/13
by
Nicholas J. McConnell; Chung-Pei Ma; James R. Graham; Karl Gebhardt; Tod R. Lauer; Shelley A. Wright; Douglas O. Richstone
texts
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We present the first direct measurement of the central black hole mass, M_BH, in NGC 6086, the Brightest Cluster Galaxy (BCG) in Abell 2162. Our investigation demonstrates for the first time that stellar dynamical measurements of M_BH in BCGs are possible beyond the nearest few galaxy clusters. We observed NGC 6086 with laser guide star adaptive optics and the integral-field spectrograph (IFS) OSIRIS at the W.M. Keck Observatory, and with the seeing-limited IFS GMOS-N at Gemini Observatory...
Source: http://arxiv.org/abs/1009.0750v2
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Sep 22, 2013
09/13
by
Edward A. Baltz; Tod R. Lauer; David R. Zurek; Paolo Gondolo; Michael M. Shara; Joseph Silk; Stephen E. Zepf
texts
eye 33
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The position of the giant elliptical galaxy M87 at the center of the Virgo Cluster means that the inferred column density of dark matter associated with both the cluster halo and the galaxy halo is quite large. This system is thus an important laboratory for studying massive dark objects in elliptical galaxies and galaxy clusters by gravitational microlensing, strongly complementing the studies of spiral galaxy halos performed in the Local Group. We have performed a microlensing survey of M87...
Source: http://arxiv.org/abs/astro-ph/0310845v3
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37
Sep 23, 2013
09/13
by
Antonela Monachesi; Scott C. Trager; Tod R. Lauer; Sebastián L. Hidalgo; Wendy Freedman; Alan Dressler; Carl Grillmair; Kenneth J. Mighell
texts
eye 37
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We use deep HST ACS/HRC observations of a field within M32 (F1) and an M31 background field (F2) to determine the star formation history (SFH) of M32 from its resolved stellar population. We find that 2-5Gyr old stars contribute \som40%+/- 17% of M32's mass, while 55%+/-21% of M32's mass comes from stars older than 5 Gyr. The mass-weighted mean age and metallicity of M32 at F1 are =6.8+/-1.5 Gyr and =-0.01+/-0.08 dex. The SFH additionally indicates the presence of young (
Source: http://arxiv.org/abs/1111.3977v1
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Sep 19, 2013
09/13
by
Richard L. White; David J. Helfand; Robert H. Becker; Michael D. Gregg; Marc Postman; Tod R. Lauer; William Oegerle
texts
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We present a new sample of 35 quasars selected from the FIRST radio survey and the Deeprange I-band survey (Postman et al. 1998, 2002). A comparison with the FIRST Bright Quasar survey samples reveals that this I-band selected sample is redder by 0.25-0.5 mag in B-R, and that the color difference is not explained by the higher mean redshift of this sample but must be intrinsic. Our small sample contains five quasars with unusually red colors, including three that appear very heavily reddened....
Source: http://arxiv.org/abs/astro-ph/0304028v1
2
2.0
Jun 27, 2018
06/18
by
Hui Dong; Zhiyuan Li; Q. Daniel Wang; Tod R. Lauer; Knut A. G. Olsen; Abhijit Saha; Julianne J. Dalcanton; Benjamin F. Williams
texts
eye 2
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We explore the assembly history of the M31 bulge within a projected major-axis radius of 180" (~680 pc) by studying its stellar populations in Hubble Space Telescope WFC3 and ACS observations. Colors formed by comparing near-ultraviolet vs. optical bands are found to become bluer with increasing major-axis radius, which is opposite to that predicted if the sole sources of near-ultraviolet light were old extreme horizontal branch stars with a negative radial gradient in metallicity....
Topics: Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1506.01097
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30
Sep 22, 2013
09/13
by
Y. I. Byun; C. J. Grillmair; S. M. Faber; E. A. Ajhar; A. Dressler; J. Kormendy; T. R. Lauer; D. Richstone; S. Tremaine
texts
eye 30
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We present a set of structural parameters for the central parts of 57 early-type galaxies observed with the Planetary Camera of the Hubble Space Telescope. These parameters are based on a new empirical law that successfully characterizes the centers of early type galaxies. This empirical law assumes that the surface brightness profile is a combination of two power laws with different slopes gamma and beta for the inner and outer regions. Conventional structural parameters such as core radius...
Source: http://arxiv.org/abs/astro-ph/9602117v1
1
1.0
Jun 29, 2018
06/18
by
Michael M. Shara; Trisha F. Doyle; Tod R. Lauer; David Zurek; J. D. Neill; Juan P. Madrid; Joanna Mikolajewska; D. L. Welch; Edward A. Baltz
texts
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The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae and nine fainter, likely very slow and/or symbiotic novae. In this first in a series of papers we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae...
Topics: Astrophysics, High Energy Astrophysical Phenomena, Solar and Stellar Astrophysics, Astrophysics of...
Source: http://arxiv.org/abs/1602.00758
0
0.0
Jun 30, 2018
06/18
by
Hui Dong; Zhiyuan Li; Q. Daniel Wang; Tod R. Lauer; Knut Olsen; Abhijit Saha; Julianne Dalcanton; Karl Gordon; Morgan Fouesneau; Eric Bell; Luciana Bianchi
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We measure the extinction curve in the central 200 pc of M31 at mid-ultraviolet to near-infrared wavelengths (from 1928A to 1.5{\mu}m), using Swift/UVOT and HST WFC3/ACS observations in thirteen bands. Taking advantage of the high angular resolution of the HST WFC3 and ACS detectors, we develop a method to simultaneously determine the relative extinction and the fraction of obscured starlight for five dusty complexes located in the circumnuclear region. The extinction curves of these clumps (RV...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1403.2691
2
2.0
Jun 26, 2018
06/18
by
Benjamin F. Williams; Julianne J. Dalcanton; Eric F. BellKaroline M. Gilbert; Puragra Guhathakurta; Claire Dorman; Tod R. Lauer; Anil C. Seth; Jason S. Kalirai; Philip Rosenfield; Leo Girardi
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We have analyzed new HST/ACS and HST/WFC3 imaging in F475W and F814W of two previously-unobserved fields along the M31 minor axis to confirm our previous constraints on the shape of M31's inner stellar halo. Both of these new datasets reach a depth of at least F814W$
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1501.06631
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Sep 20, 2013
09/13
by
Carl J. Grillmair; S. M. Faber; Tod R. Lauer; J. J. Hester; C. R. Lynds; E. J. O'Neil, Jr.; P. A. Scowen
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We present high-resolution, broad- and narrow-band, pre-refurbishment images of the central region of M51 taken with the Planetary Camera of the Hubble Space Telescope. The V-band images show a rather chaotic distribution of dust lanes, though some are oriented radially, roughly aligned with the major axis of the bar, and may be transporting gas to the AGN in the nucleus. The dust lane obscuring the nucleus of the galaxy, which was previously thought to be an edge-on accretion disk feeding the...
Source: http://arxiv.org/abs/astro-ph/9610111v1
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Sep 24, 2013
09/13
by
Nicholas J. McConnell; Chung-Pei Ma; Karl Gebhardt; Shelley A. Wright; Jeremy D. Murphy; Tod R. Lauer; James R. Graham; Douglas O. Richstone
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Observational work conducted over the last few decades indicates that all massive galaxies have supermassive black holes at their centres. Although the luminosities and brightness fluctuations of quasars in the early Universe suggest that some are powered by black holes with masses greater than 10 billion solar masses, the remnants of these objects have not been found in the nearby Universe. The giant elliptical galaxy Messier 87 hosts the hitherto most massive known black hole, which has a...
Source: http://arxiv.org/abs/1112.1078v1
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1.0
Jun 29, 2018
06/18
by
Hui Dong; Zhiyuan Li; Q. D. Wang; Tod R. Lauer; Knut A. G. Olsen; Abhijit Saha; Julianne J. Dalcanton; Brent A. Groves
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We map the dust distribution in the central 180" (~680 pc) region of the M31 bulge, based on HST/WFC3 and ACS observations in ten bands from near-ultraviolet (2700 A) to near-infrared (1.5 micron). This large wavelength coverage gives us great leverage to detect not only dense dusty clumps, but also diffuse dusty molecular gas. We fit a pixel-by-pixel spectral energy distributions to construct a high-dynamic-range extinction map with unparalleled angular resolution (~0.5" , i.e., ~2...
Topics: Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1603.09637
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62
Sep 18, 2013
09/13
by
Benjamin F. Williams; Julianne J. Dalcanton; Eric F. Bell; Karoline M. Gilbert; Puragra Guhathakurta; Tod R. Lauer; Anil C. Seth; Jason S. Kalirai; Philip Rosenfield; Leo Girardi
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We attempt to constrain the shape of M31's inner stellar halo by tracing the surface density of blue horizontal branch (BHB) stars at galactocentric distances ranging from 2 kpc to 35 kpc. Our measurements make use of resolved stellar photometry from a section of the Panchromatic Hubble Andromeda Treasury (PHAT) survey, supplemented by several archival Hubble Space Telescope observations. We find that the ratio of BHB to red giant stars is relatively constant outside of 10 kpc, suggesting that...
Source: http://arxiv.org/abs/1209.2416v1
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26
Sep 20, 2013
09/13
by
S. M. Faber; Scott Tremaine; Edward A. Ajhar; Yong-Ik Byun; Alan Dressler; Karl Gebhardt; Carl Grillmair; John Kormendy; Tod R. Lauer; Douglas Richstone
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We analyze Hubble Space Telescope surface-brightness profiles of 61 elliptical galaxies and spiral bulges (hot galaxies). Luminous hot galaxies have cuspy cores with steep outer power-law profiles that break at r ~ r_b to shallow inner profiles with logslope less than 0.3. Faint hot galaxies show steep, largely featureless power-law profiles at all radii and lack cores. The centers of power-law galaxies are up to 1000 times denser in mass and luminosity than the cores of large galaxies at a...
Source: http://arxiv.org/abs/astro-ph/9610055v2
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51
Jul 20, 2013
07/13
by
Nicholas J. McConnell; Chung-Pei Ma; Jeremy D. Murphy; Karl Gebhardt; Tod R. Lauer; James R. Graham; Shelley A. Wright; Douglas O. Richstone
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We present stellar kinematics and orbit superposition models for the central regions of four Brightest Cluster Galaxies (BCGs), based upon integral-field spectroscopy at Gemini, Keck, and McDonald Observatories. Our integral-field data span radii from < 100 pc to tens of kpc. We report black hole masses, M_BH, of 2.1 +/- 1.6 x 10^10 M_Sun for NGC 4889, 9.7 + 3.0 - 2.6 x 10^9 M_Sun for NGC 3842, and 1.3 + 0.5 - 0.4 x 10^9 M_Sun for NGC 7768. For NGC 2832 we report an upper limit of M_BH <...
Source: http://arxiv.org/abs/1203.1620v2
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33
Sep 22, 2013
09/13
by
Joseph B. Jensen; John L. Tonry; Rodger I. Thompson; Edward A. Ajhar; Tod R. Lauer; Marcia J. Rieke; Marc Postman; Michael C. Liu
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We measured infrared surface brightness fluctuation (SBF) distances to an isotropically-distributed sample of 16 distant galaxies with redshifts reaching 10,000 km/s using the near-IR camera and multi-object spectrometer (NICMOS) on the Hubble Space Telescope (HST). The excellent spatial resolution, very low background, and brightness of the IR fluctuations yielded the most distant SBF measurements to date. Twelve nearby galaxies were also observed and used to calibrate the F160W (1.6 micron)...
Source: http://arxiv.org/abs/astro-ph/0011288v1
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Sep 22, 2013
09/13
by
C. J. Grillmair; E. A. Ajhar; S. M. Faber; W. A. Baum; J. A. Holtzman; T. R. Lauer; C. R. Lynds; E. J. O'Neil Jr.
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We analyze post-refurbishment Hubble Space Telescope images of four globular clusters in M31. The ability to resolve stars to below the horizontal branch permits us to use star counts to extend the surface brightness profiles determined using aperture photometry to almost 5 orders of magnitude below the central surface density. Three of the resulting cluster profiles are reasonably well-fit using single-mass King models, with core and tidal radii typical of those seen in Galactic globular...
Source: http://arxiv.org/abs/astro-ph/9602047v1
